Improve docker support

- Add docker-compose file
- Add environment variable to initialize the database
- Add custom entrypoint that generates the .env file based on the environment variables
- Update Dockerfile (gettext-base package)

docker/entrypoint.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+
+cat .env.docker | envsubst > .env
+
+if [ "${INIT_DATABASE:="no"}" = "yes" ]; then
+	echo "Init database detected, checking mysql status"
+	# depends on your machine, but it may take a file to boot mysql container the first time
+	until php artisan firefly:verify &>/dev/null
+	do
+  		echo "waiting mysql"
+  		sleep 10 
+	done
+	php artisan migrate:refresh --seed
+fi
+
+exec apache2-foreground